#include <reg52.h>
#include <intrins.h>
#define uint unsigned int
#define uchar unsigned char
void delayms (uint i);
uchar aa;
void main()
{
 aa=0xfe;
 while(1)
 {
  P1=aa;
  delayms(500);
  aa=_crol_(aa,1);
 }
}
void delayms (uint xms)
{
  uint i,j;
  for(i=xms;i>0;i--)
   for(j=110;j>0;j--);
}
